Firefighters extinguished an electrical fire on the roof of a strip mall in San Lorenzo early Tuesday morning, and investigators believe the fire may have been started by thieves attempting to steal copper wiring, a fire spokeswoman said.

The fire threatened other businesses connected to the Naked Fish Japanese Cuisine, located at 24703 Amador St. in a strip mall, but firefighters were able to contain the blaze before it spread elsewhere, fire Capt. Thor Poulsen said.